Children of people who used weed during pregnancy may have a higher risk of severe anxiety and aggression, a small study finds

• Children of mothers who use cannabis during pregnancy are more likely to be anxious and hyperactive, says a study of 322 babies and their moms.
• The study authors tested the placental tissue of moms who did and did not use cannabis during pregnancy. They also analyzed the children's behaviors until age 6.

Children who were exposed to cannabis via their mother's placenta are more likely to exhibit high anxiety, aggression, and hyperactivity, according to a small study published in Proceedings of the National Academy of Sciences.

As an increasing number of pregnant people consider cannabis as an alternative for nausea and pain relief, studying the ways it can affect a pregnant person and their babies has become vital, Yasmin L. Hurd, lead study author and director at the Addiction Insitute of Mount Sinai, told Scientific American.

"Our studies are about empowering them with knowledge and education so that they can make decisions," Hurd told Scientific American.

This study is one of the first to directly examine the link between cannabis and how it affects human offsprings, outside expert Daniele Piomelli, director of the Center for the Study of Cannabis at the University of California, Irvine, told Scientific American.

Existing research remains limited and isn't conclusive, so doctors suggest pregnant people abstain from using cannabis throughout gestation, Insider previously reported. Cannabis use during pregnancy could potentially increase the risk of low birth weight and preterm delivery and autism in children, Insider previously reported.

322 babies were monitored in the womb until age 6

To study how cannabis use during pregnancy could affect babies in the womb, Hurd and her team studied 322 parents and their children, from the time they were born until the babies turned 6.

When each baby was born, the researchers used samples from their mothers' placentas and tested the genetic composition of each. When the babies turned 3, researchers tested their hair and heart rates to analyze their responses to stress.

They also performed evaluations for anxiety, hyperactivity, and aggression, while controlling for outside factors like cigarette exposure and the parents' anxiety levels. The study authors performed these tests until the babies turned 6.

They found babies whose mothers used cannabis during pregnancy were more likely to have had underfunctioning placental tissue, which can decrease immune system response, according to the study authors. Children whose mothers used cannabis were also more likely to feel anxious and appear hyperactive.

More research is needed, since other factors can impact aggression and stress

The study had some limitations.

Since children can develop stress, high anxiety, aggression and hyperactivity for a number of reasons, like their parents' age and marital status or their race and sex, it's unclear whether cannabis caused the adverse outcomes in the study's participants, Hurd told CNN.

Additionally, the mothers in the study self-reported their cannabis use, so the study authors couldn't be sure of their exact intake, or the mothers' history of cannabis use before pregnancy.